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Dental Materials > Summary cards > Flashcards

Summary cards Flashcards

1
Q

What is the composition of dental amaglam?

A

50% mercury
50% metal alloy

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2
Q

what is in dental amalgam alloy?

A

silver, tin, copper, zinc

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3
Q

what is silver and coppers properties in dental amalgam?

A

strength

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4
Q

what is tins properties in dental amalgam?

A

corrosion

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5
Q

what is zincs properties in dental amalgam?

A

deoxidiser - prevents oxidisation of other metals in the alloy

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6
Q

what happens to zinc in dental amalgam is contaminated with moisture?

A

it can expand

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7
Q

what is it called when amalgam is mixed?

A

trituration

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8
Q

what components are involved in the setting reaction of dental amalgam?

A

mercury and silver

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9
Q

what does dental amalgam setting reaction involve in?

A

3 phases:
Y
Y1
Y2

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10
Q

What is the Y phase of dental amalgam setting?

A

unreacted silver-tin alloy

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11
Q

what is the Y1 phase of dental amalgam setting?

A

strong silver-mercury matrix

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12
Q

what is the Y2 phase of dental amalgam setting?

A

weak tin-mercury

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13
Q

why is the Y2 phase of dental amalgam setting weak?

A

susceptible to corrosion and creep

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14
Q

what is creep?

A

deformation of amalgam under compressive stress

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15
Q

on trituration what are the dimensional changes?

A

30mins shrinkage
30-60mins

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16
Q

what is an advantage of corrosion products?

A

margin seal

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17
Q

when does dental amalgam reach its peak strength?

A

24 hours

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18
Q

what are the 2 alloy types for dental amalgam?

A

conventional
high copper

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19
Q

what percentage of copper differentiates types of amalgam alloys?

A

12%

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20
Q

why is high copper alloy better for dental amalgam?

A

doesnt result in Y2 phase = less corrosion and creep

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21
Q

what are the 2 types of dental amalgam alloy particles?

A

spherical and admixed (spherical and lathe-cut)

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22
Q

what are 3 advantages of a spherical alloy for dental amalgam?

A

easier to condense
stronger
sets faster

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23
Q

what is an advantage of an admixed alloy particle for dental amalgam?

A

better proximal contact

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24
Q

what minimum depth should amalgam be placed in?

A

2mm

25
Q

how should dental amalgam be placed and filled?

A

in 2mm increments
overpack
carve back mercury layer

26
Q

are enamel or dentin bonds weaker?

A

dentine

27
Q

why are enamel bonds stronger than dentine?

A

enamel has more mineral content
enamel rods are parallel and more etchable

28
Q

why has dentine got weaker bonds than enamel?

A

more organic matter and water
collagen fibres that are maze like
dentinal fluid
smear layer

29
Q

what is used for acid etching?

A

30-40% phosphoric acid

30
Q

how long do you leave acid etch on for?

A

15 seconds

31
Q

what does acid etching do?

A

cleans surface debris and removes smear layer
widens dentinal tubules

32
Q

what does enamel look like after it has been etched?

A

frosty white

33
Q

what component of primer allows for a good bond?

A

HEMA

34
Q

How does HEMA allow for a good bond?

A

infiltrates enamel prisms and dentinal tubules and WETS dentine to prevent collagen collapsing

35
Q

what are the contraindications of HEMA in primers?

A

can cause allergic reaction on skin - contact dermatitis

36
Q

What is the component of bond/ adhesive?

A

Bis-GMA

37
Q

What does bond/ adhesive do?

A

chemically bonds to underlying primer and overlying composite resin

38
Q

what is the key to great bond strength?

A

hybrid layer

39
Q

what does the hybrid layer create?

A

mechanical interface between tooth and adhesive

40
Q

what are resin tags?

A

extensions of primer into dentinal tubules

41
Q

what is resin composite made of?

A

resin matrix (Bis-GMA) and glass filler particles (silica)

42
Q

what is in resin composite that promotes adhesion between resin matrix and filler?

A

coupling agent

43
Q

what does coupling agent do in resin composites?

A

coats filler particles to promote adhesion between resin matrix and filler

44
Q

what makes resin composite radioopaque?

A

filler

45
Q

what setting reaction does resin composite undergo?

A

polymerisation

46
Q

what are the 2 pastes involved in self curing composite?

A

benzoyl peroxide (initiator)
tertiary amine (activator)

47
Q

what component allows composite to be light cured?

A

camphorquione (photo initiator)

48
Q

how strong does light need to be to initiate polymerisation?

A

468nm

49
Q

What makes up a glass ionomer?

A

acid (polyacrylic acid)
base (aluminosilicate glass)

50
Q

what are the good properties of glass ionomer?

A

self-adhesion to tooth
fluoride release
less overall shrinkage

51
Q

what process makes glass ionomer self adhesive?

A

chelation

52
Q

what are the bad properties of glass ionomer?

A

weaker
longer setting time
lack of control when setting

53
Q

adding light curing resin to glass ionomer makes it a?

A

resin-modified glass ionomer

54
Q

what setting reactions do resin-modified glass ionomers undergo?

A

acid base
free radical addition polymerisation

55
Q

what ways can resin-modified glass ionomers be set?

A

light and/or chemical

56
Q

what is vitrebond??

A

resin-modified glass ionomer liner

57
Q

what are good properties of resin modified glass ionomers?

A

more rapid polymerisation
fluoride release

58
Q

if a cavity is deep to pulp what would you use before vitrebond and why?

A

dycal as vitrebond is an irritant to pulp

Dental Materials (9 decks)

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